I'm running higher boost (8lb) on my non-Aftercooled Comptech SC. I notice that if I have been driving aggressively then back off, the next time I open the throttle I get a bit of a choke. I assume this is because hot charge from the bypass valve is in the intake tract and this is getting sucked into the engine. I think the IAT sensor is seeing this and pulling ignition drastically.

If I'm not mistaken the difference between a BOV and bypass is that the BOV vents to atmosphere whereas the bypass vents to the intake tract. If this is the case I could disconnect the bypass valve from the intake tract, put a bung in the intake flange and point the bypasses outlet down. Instant BOV!

Is this correct? I realise the proper solution is an AC with BOV but funds don't currently permit.

 

Rough idle.

 

Is that a question or a statement or what?

 

Aus, from what I understand how Bypass valves work, the only reason it's a bypass valve is due to the fact the air is recycled back into the air intake. So if you plug the hole in the air tube, The bypass valve should work as a BOV.

 

Isn't there a vacuume hose connected on the c/t bypass valve. If you just bunk the hole where it sits, that sounds like a bad idea unless you get a bov. Mine has the vacume line attached to my bov

 

Did you get the 8lb pully from tech2? I thinking about it getting one. what did you have to change to run that boost level?

 

Forget the rough idle comment. I misread your post...



Either way, I don't think the boost bypass solenoid opens/closes based on MAP, but on TPS.

I say hook up a scanner, recreate the condition (drive hard, back off, floor it), and make a "movie" with your scan tool. Pay attention to your STFT, IAT, and spark advance.

 

It sounds like the vacuum line is to operate the BOV/bypass - I guess it's not electronic, but vacuum-actuated.

I retract my previous "MAP rather than TPS" comment.

 

Alexf20c - You realise the net result of your posts is 0.

The bosch bypass valve is vacuum operated. There is a 4mm vacuum line from the intake to the device. A vacuum state opens to valve and bypasses the charge to the intake tract.

The idea is to not apply pressure to the throttle butterfly when it is closed and avoid back pressure on the SC compressor fins.

Venting to intake I believe is a CARB thing and not actually necessary.

swtazn97 - I'm not sure who made my pulley. I bought the SC second hand and it came with it as a spare. It's 4".

I have replaced the FPR with a SARD unit with a 1:1 ratio (but better flow than the OEM), replaced the injectors with 440cc RC Eng/Lucas units, and run the thing with an E-manage.

Runs pretty good except on hot days (and it's summer here). An AC and decent BOV is the solution I think.

 

Actually, net result would equal -1.